The Echinoid Directory

• Test up to 55 mm in diameter; flattened and discoidal in shape with marked change between aboral and oral plating; pentagonal in outline.
• Apical disc small; monocyclic; genital plates larger than ocular plates. One genital plate pierced by hydropores; all genital plates with multiple gonopores arranged as an arc.
• Ambulacra on aboral surface relatively narrow and straight; composed of 6 columns of small hexagonal plates in the type species, each with a pore-pair; no tubercles. On the oral surface ambulacral zones greatly expanded and forming most of the surface, with 6 columns of hexagonal plates; pore-pairs in outer two columns of two kinds - alternately small pore-pairs without peripodial rim, and large circular pore-pairs with pronounced peripodial rim. Pore-pairs of inner column entirely small. Ambulacral plates imbricate adorally.
• Interambulacra with up to 6 columns of rhomboidal plates, imbricating strongly adapically. Adorally the interambulacra are greatly constricted narrowing to a single column and not reaching the peristome.
• No primary tubercles aborally, only secondary granulation. Primary tubercles present adorally on interambulacral and ambulacral plates; no pronounced areolar depression; scattered secondary tubercles on interambulacral plates.
• Primary spines short and simple.

Upper Permian, Turkey.

Pronechinus anatoliensis Kier, 1965, p. 462, by original designation.

• Only the type species.

Stem group Echinoidea; Proterocidaridae.

Monotypic.

Similar to Proterocidaris in having the adoral and adapical surfaces very different and in the greatly expanded adoral ambulacral zones. Differing from that taxon in having two types of pore-pair on oral ambulacral plates, small simple pore-pairs as well as large circular pore-pairs.

Kier, P. M. 1965. Evolutionary trends in Paleozoic echinoids. Journal of Paleontology 39, 436-465, pls 55-60.